A legally blind person is someone who would have to stand 6 metres from a particular object to see it with the same degree of clarity that a person with normal normal vision can from a distance of 60 metres. The visual field of a legally blind person is also limited to 20 degrees or less. A person with normal site has a field of vision measuring 180 degrees.
Normal visual acuity is termed as 20/20 (or 6/6). If the second number is smaller (say 20/18 or 6/5.4) it means the person has better than normal vision. Conversely, if the second number is larger (say 20/22 or 6/6.6), it means the person has worse than normal vision.
Governments all over the world have had to define legal blindness in order to decide eligibility for special benefits. For instance, legally blind person in the US can receive disability payment, take help of note takers and writers in college and avail of Seeing Eye dogs and white canes.
Marla Runyan, an American marathon runner, was the first legally blind athlete to participate in the Olympics–at Sydney in 2000.
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